Roasting of sulfur-bearing ores.



' H. H. STOUI. ROASTING 0F SULFUR BEARING ORES.l

APPLICATION man JuLYl. 1914. l

H. H. STOUT.

ROASTING 0F SULFUR BEARING ORES.

APPLICATION mso :uw 31.1914.

Patented May 2, w16.

2 SHEETS-SHEET 2.

` Amm/frs 'some extent be HARRY H. STOUT, OF NEW YORK,

N. Y., ASSIGNOR TO GENERAL CHEMICAL COMPANY,

OF NEW YORK,.N. Y., A CORPORATION 0F NEW YORK.v

To all whom t may concern:

Be it known that I, HARRY H. STOUT, a-

citizen of the United States, and a resident of the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in the Roasting of Sulfur-Bearing Ores, of which the following, taken in connection with the accompanying drawings, is a specification. `My invention relates to the roasting of sulfur-bearing ores, especially in connection with a'rotary roasting furnace of the type shown in United States Letters Patent, No. 976,175 to John B. F. Herreshoif, dated November 22, 1910, and the object of my invention is to provide a regulatable distribution of heat, and controllable temperature conditions on each of the several roasting hearths orv shelves ofsuch a furnace. It has long been known that an obstacle to the most economical and eicient operation of furnaces of this type is the formation of incrustations which clog up the moving parts of the furnace, or of scars, z'. c. fused massesof the material undergoing roasting, which attach themselves with more or less firmness tol the hearth surface or to the rabble teeth or to both, thus bringing about ineliciencies in operation dueto stoppage and due to the physical condition of the agglomerated material, which renders it incapable of being deprived of its sulfur contentto the extent necessary for successful commercial operation. These scars or incrustations usually form in the upper hearth lspaces the temperature of which is apt `to vbe excessively high while the lower the same time at a temperature which' is usually too low for eiicient operation. If, as has` been proposed, the furnace is operated at below normal capacity, the formation of these agglomerated masses may to prevented, but -such operation -is obviously inefficient and-is not capable of being controlled. i

I have found that by a proper transfer of the heat generated on any hearth in excess of that heat necessarv u 'top bring about satisfactory roasting, to some other hearth having insufficient heat 0r temperature con'- ditions, satisfactory roasting can be effected, coupled with a capacity per -day greater Specication of Letters Patent.

hearth spaces are atl stood, of course,

Patented May 2, i916.

Application led July 31, 1914. Serial No. 854,230.

than under the most favorable conditions heretofore obtaining; that by so operating 1t 1s possible to have fewer interruptions than under the best practice heretofore obtaining, and 'fewer repair charges.

In order to make clear the nature of my invention and to explain fully the process .thereof I will now refer to the accompanylng drawings 1n whlch 1s shown a roasting furnace by the use of which the process of my invention may be carried out, 1n which drawings* Y Figure l shows the furnace in central vertical section, and Fig. 2 shows a plan view thereof, certain parts being in section.

The furnace illustrated comprises a number of superposed hearths l extending inwardly from an outer, cylindrical wall 2 and providing roasting spaces between the hearths, which spaces are traversed by rabble or stirring arms 3, rotatably supported by a central, vertical double-walled shaft 4. Through the central passage of the shaft, air or other suitable cooling medium is' forced, from which passage it passes through the several rabble arms in parallel and issues therefrom into the annular passage of'the shaft, which surrounds the central passage thereofiwe 'A In communication with the top of the annular channel of the shaft is a transverse conduit 5, the ends of which connect with the bustle pipe 6, the latter being in the form of a ring of approximately the same diameter as the furnace itself and being supported upon the cylindrical wall 2 of the furnace. The bustle pipe communicates with a plurality of vertical flues or conduits 7, preferably metallic, which are built into the wall 2, so that their inner walls are in direct contact with the products of roasting in the furnace hearth-spaces and which extend from the bustle pipe to the lowest hearth-space. Air or other fluid is thus capable of being conducted by the conduits 7 from the bustle pipe to the roasting space of the said lowest hearth. It will be underthat the conduits may discharge into other hearth `spaces than the lowest one and that certain of them may discharge into the lowest space while others of them may discharge intol other roasting spaces. I have found, however, that Successful and efficient operation may be had in practice with a furnace in which all of the conduits 7 discharge into the lowermost roasting space.

'An outlet into the atmosphere is provided in the form of a stack 8 which may extend upwardly from the transverse conduit and is provided with a valve or damper a. A pipe 9 insulated from the heat of the furnace, or a plurality of such pipes, connects with the conduit 5 and eX- tends downwardly; the lower end of 'said pipe is in communication with the inlet conduit 10 which communicatesat one end with the central passage of the shaft 4 and which is adapted to convey cooling air from a fan or otherfluid-forcing apparatus (not z shown) into the shaft and, if desired, into the pipe 9, the latter preferably lcommunicating with the conduit 10 at a point located between the fan andthe shaft. A branch pipe 11 establishes communication between each pipe 9 and one or more of the roasting spaces, as for example, that of the lowermost hearth into which the lues or conduits 7 also discharge. The transverse conduit 5 is provided with dampers b located between -the shaft 4 and the outlet 8 on the one hand and the bustle pipe 6 and the pipe 9 on the other hand. Dampers 0 are provided between the transverse conduit and the bustle pipe; dampers d and e are provided in the pipes 9 respectively above and below the point of communication between said pipes andthe branch pipes 11; and the branch pipes 11 are themselves provided with dampers f.

The device illustrated is adapted to be operated in a number of ways which will depend upon the nature and qualities of the ore being roasted, which ores may be, for example, iron pyrites, copper pyrites, pyrrhotite, blende, galena or various mixtures thereof. According to each method of operation, however, air, or other suitable cooling fluid, which has extracted a certain amount of heat from the furnace by being forced through the rotary stirring system and which has thus been raised to a temperature which approaches the average temperature of the various roasting spaces or zones is passed into heat exchanging prox- 1m1ty to all of the roasting zones of the furnace and then discharged into a relatively cooler Zone thereof, so as` substantially to extract heat from the zones the temperatures of which are higher than said air temperature and add heat to Zones the temperatures of which are lower than said air temperature, thus causing the temperature of the various Zones to approach the temperature of said air. In other words, the cooling air, after it has traversed the shaft and rabble arms ,of the rotary stirril'i'g system, 1s caused to pass through the codiutsTad to extract heat from the hotter roasting spaces and add heat to the cooler roasting spaces, this heat exchange being practically accomplished in view of the fact that said conduits. are made of material which conducts heat readily, said material being exposed to and in direct contact'with the atmosphere of said roasting spaces; after being thus subjected to heat exchange, the air is conducted, as shown, into the lowermost roasting space.

According to one method `of operationT the dampers, a, (Z, and f are closed and the dampers and c are open, the dampers c being either open or closed. Air isforced by the fan through the conduit 10 and passes therefrom into and through the rabble arm system from which it issues into the transverse conduit 5 and passes therefrom successively into the bustle pipe 6 and heat exchanging conduits 7, lfinally discharging into the lower hearth space. If desired, the damper a. ma)y be opened slightly and if necessary the dampers Z) and o be closed slightly so as to cause any controlled proportion of the air 4to pass from the transverse conduit into the atmosphere through the stack 8, and the remainder to pass through the conduits 7 into the lowermost combustion chamber. Further heat control may be had by opening the dampers (l and f more or less and closing the damper e, the

damper L being either open or closed, so that a portion of the air will pass `down through the pipe- 9 into the branch 11 and discharge into the lower hearth space. It is obvious that a suitable manipulation of the dampers will result in causing all of the air to pass into the atmosphere through the exit S, all of it to pass through the heat interchanging conduits 7 into the lower portions of the furnace. all of it to pass through the external pipe 9 into said lower portions, all of it to pass through any two of these passages 7 8 and 9, or any proportion of it to pass through these two or three passages. It will be seen that the furnace is very iexible in its operation and can be accommodated to the roasting of any kindof ore. It is further-possible to manipulate the dampers in an obvious manner so as to cause Y.

and serving to regulate and control the heat and temperature of the furnace by extracting heat from the upper portions of the furnace, which heat has been conducted from the chamber through the metal forming the said conduits 7, and conveying such' extracted. heatinto the lower portions of the furnace.. v

I claim: l Y

1. In the art of roasting vsulfur-bearing ores, the improvement, which comprises first heating air to a temperature which approaches the average temperature of the various roasting zones, then passing la volume of the heated air into heat exchanging proximity to all of the roasting zones,

`whereby heat is substantially extracted from yzones the temperatures of which are higher -than said air temperature and added to Zones the temperatures of which are lower than saidair temperature, thus causing the temperatures of the various zones to approach the temperature of said air,' and finally 'introducing the air into a .relatively cool roasting zone,substa ntially as and for the purpose described.

2. In th heatingI Vmy hand e art of roasting sulfur-bearing j` ores, the improvement which comprises irst air to a` temperature which ap- 'proaches the average temperature of the `the temperatures-'of which are higher thanv sald air temperature and addedto Zones the temperatures of which are lower than said air temperaturenthus causing the tempera` tures of the varlous zones to approach the temperature of said air, and nally intro'- ducing the air into a relatively cool roasting Zone, substantially as and for the purpose described.

In testimony whereof I have hereunto set in the presence of two subscribing witnesses.

HARRY H. STOUT. IVitnesses:

JOHN A. FERGUSON, FRED A. KLEIN. 

